1. Reaction Predictions Precipitation Reactions

2. Precipitation Prediction 1)Write the reactants in ionic from o breakdown into ionic form if compounds are soluble o leave as molecules if insoluble 2)Determine the solubility of the products. o Use solubility Rules

3. Precipitation Predictions (cont.) 3) Check to see if one product is insoluble in water. o Product will fall out of solution, identified as precipitate 4) Write the net ionic equation o Displays which ions are directly involved in the reaction, produce the precipitate o Ions existing on BOTH sides of the equation are “ spectator ions ” (do NOT participate in precipitate formation) o Spectator ions are eliminated

4. Example 1: Na 2 SO 4 + MgCl 2 Write the net ionic equation. Will a precipitate form?

5. Example 2: MgSO 4 + KOH Write the net ionic equation. Will a precipitate form?

6. Example 3: YOU TRY! KNO 3 + MgSO 4 Write the net ionic equation. Will a precipitate form?

7. What is the purpose of precipitation reactions? 1)Production of a particular chemical compound 2)Sample analysis of a chemical compound o Use actual vs. theoretical yield to determine the % yield of a product o Determine the amount of precipitate formed in the reaction o If the chemical source of an ion is KNOWN, determine the quantity of that chemical source present for the reaction

8. Example 1: A 240 g sample of chicken broth combined with excess AgNO 3 (aq) produces 4.302 g AgCl. If all Cl – ions originate from NaCl, how much salt is present in the chicken broth (in grams)?

9. Example 2: A white precipitate is formed when an unknown white solid is dissolved into a solution and reacted with Ba(NO 3 ) 2. Arthur with the help of Merlin has narrowed the identity of the unknown solid to be 3 possibilities: MgCl 2, MgSO 4, or Mg(NO 3 ) 2. Identify the unknown.